Windows form to collect data

Question

I have a dialog box for the user to fill in information for a post (post name, post description, etc), then, when the user press "ok" it will start the user control constructor to build a post with the data given. It's a code a found in an old program of mine and edit it for the current requirements. I get an error when trying to run the UserControl1 constructor. An object reference is required for the nonstatic field, method, or property"

public partial class Form1 : Form
{
    private UserControl1 Post_Storage;
    public Form1()
    {
        InitializeComponent();
    
    }

    private void button1_Click(object sender, EventArgs e)
    {
        string input = "";
        ShowInputDialog(ref input);
    }
    /// <summary>
    ///  type = DialogResult
    /// </summary>
    
    private static void ShowInputDialog(ref string input)
    {
        System.Drawing.Size size = new System.Drawing.Size(325, 350);
        Form inputBox = new Form();

        inputBox.FormBorderStyle = System.Windows.Forms.FormBorderStyle.FixedDialog;
        inputBox.ClientSize = size;
        inputBox.Text = "Add a new post"; ///window name

        ////////
        Label PostName = new Label();
        PostName.Text = "Post Name:";
        PostName.Size = new System.Drawing.Size(size.Width - 10, 23);
        PostName.Location = new System.Drawing.Point(10, 10);
        inputBox.Controls.Add(PostName);

        System.Windows.Forms.TextBox NametextBox = new TextBox();
        NametextBox.Size = new System.Drawing.Size(size.Width - 10, 23);
        NametextBox.Location = new System.Drawing.Point(10, 35);
        inputBox.Controls.Add(NametextBox);
        //////////

        ////////
        Label PostDis = new Label();
        PostDis.Text = "Post Description:";
        PostDis.Size = new System.Drawing.Size(size.Width - 10, 23);
        PostDis.Location = new System.Drawing.Point(10, 60);
        inputBox.Controls.Add(PostDis);

        System.Windows.Forms.TextBox DistextBox = new TextBox();
        DistextBox.Size = new System.Drawing.Size(size.Width - 10, 23);
        DistextBox.Location = new System.Drawing.Point(10, 85);
        inputBox.Controls.Add(DistextBox);
        //////////

        ////////
        Label PostURL = new Label();
        PostURL.Text = "Video URL:";
        PostURL.Size = new System.Drawing.Size(size.Width - 10, 23);
        PostURL.Location = new System.Drawing.Point(10, 110);
        inputBox.Controls.Add(PostURL);

        System.Windows.Forms.TextBox URLtextBox = new TextBox();
        URLtextBox.Size = new System.Drawing.Size(size.Width - 10, 23);
        URLtextBox.Location = new System.Drawing.Point(10, 135);
        inputBox.Controls.Add(URLtextBox);
        //////////

        ////////
        Label PostTag = new Label();
        PostTag.Text = "Tags (Please add related tags decribing the video \n and separate them using #. exp: #Tag #Tag2):"; 
        ////*max of 5 tags per video.
        ///when user tries to add more than 5 tags, a message will pop, asking to remove.
        PostTag.Size = new System.Drawing.Size(size.Width - 10, 35);
        PostTag.Location = new System.Drawing.Point(10, 160);
        inputBox.Controls.Add(PostTag);

        System.Windows.Forms.TextBox TagtextBox = new TextBox();
        TagtextBox.Size = new System.Drawing.Size(size.Width - 10, 23);
        TagtextBox.Location = new System.Drawing.Point(10, 195);
        inputBox.Controls.Add(TagtextBox);
        //////////
        Button okButton = new Button();
        okButton.DialogResult = System.Windows.Forms.DialogResult.OK;
        okButton.Name = "okButton";
        okButton.Size = new System.Drawing.Size(75, 23);
        okButton.Text = "&ADD";
        okButton.Location = new System.Drawing.Point(size.Width - 240 - 80, 300);
        inputBox.Controls.Add(okButton);

        Button cancelButton = new Button();
        cancelButton.DialogResult = System.Windows.Forms.DialogResult.Cancel;
        cancelButton.Name = "cancelButton";
        cancelButton.Size = new System.Drawing.Size(75, 23);
        cancelButton.Text = "&Cancel";
        cancelButton.Location = new System.Drawing.Point(size.Width - 240, 300);
        inputBox.Controls.Add(cancelButton);

        inputBox.AcceptButton = okButton;
        inputBox.CancelButton = cancelButton;

        String Post_Name = NametextBox.Text;
        String Post_Dis = DistextBox.Text;
        String Post_URL = URLtextBox.Text;
        String Post_Tags = TagtextBox.Text;
        ///MessageBox.Show(Post_Name);
        DialogResult Name = inputBox.ShowDialog();
        input = NametextBox.Text;
        ///DialogResult dis = inputBox.ShowDialog();
        ///input = DistextBox.Text;
        ///DialogResult URL = inputBox.ShowDialog();
        ///input = URLtextBox.Text;
        ///DialogResult Tags = inputBox.ShowDialog();
        ///input = TagtextBox.Text;

        if (inputBox.DialogResult == DialogResult.OK)
        {
            // Display a message box indicating that the OK button was clicked.
            MessageBox.Show("Added the post.");
            // Optional: Call the Dispose method when you are finished with the dialog box.
            // in here we are going to run the constructor builder for the new post, from the UC constructor. 
            Post_Storage = new UserControl1(Post_Name, Post_Dis, Post_URL, Post_Tags);
            Post_Storage.Location = new Point(50, 50);
            this.Controls.Add(Post_Storage);
            inputBox.Dispose();
        }
        else
        {
            // Display a message box indicating that the Cancel button was clicked.
            MessageBox.Show("Upload canceled.");
            // Optional: Call the Dispose method when you are finished with the dialog box.
            inputBox.Dispose();
        }
    }